I would be happy to help you with your question about your dog. I have a few questions to ask if you don't mind answering them so I can get a clearer idea of what's happening with your dog?Is your dog male or female?Is s/he spayed or neutered?Is only one nipple red and inflamed?Are there any other spots on the skin that are red, or spots of hair loss?
Thank you for taking the time to answer my questions!Since she's experiencing hair loss in other areas, it's possible she could be dealing with allergies, or even an endocrine disorder such as hypothyroidism, which can cause the spots of irritation and hair loss that you are seeing on various parts of her body.These can cause skin to become dry and itchy, including the area of the nipples. If she has licked/chewed at this area or rubbed it along the floor to scratch at it, it's possible to have even further inflamed the skin to the point where it has become swollen. There is even the possibility that this spot could have developed a secondary bacterial infection.Your next step would be to get her into the vet to take a look at the nipple to determine if she will need some antibiotics to help get rid of the swelling in that particular nipple due to a bacterial infection. Your vet can also do testing for disorders such as hypothyroidism that might be causing the dry skin and hair loss along her back, so you can give her the appropriate medication to help prevent these spots from reoccuring, and help her re-grow the hair on her back.If it is something like a flea allergy, you will need a flea treatment to help kill the fleas which are causing the irritation and hair loss. Your vet can talk to you about the use of over-the-counter Benadryl to help reduce the symptoms of allergies in conjunction with flea treatments (or other types of allergies if she is on flea prevention and isn't bothered by fleas).Along those same lines, there is always the possibility that she has a fungal skin infection, lice, or mites. A deep skin scraping will allow your vet to see mites under the microscope, and prescribe a medication to get rid of them. Lice are visible to naked eye, so your vet would be able to distinguish them from fleas, and prescribe a medicated shampoo to help get rid of them. A fungal infection like ringworm would require a culture to diagnose, but it is also treatable through an oral anti-fungal medication, or in the case of a localized infection, a topical ointment.As you can see, there are a lot of reasons that your girl's poor skin can become inflamed, and since she has other areas and spots that are experiencing redness or loss of hair, your next best step would be to get her into the vet to do a differential diagnoses to determine which type of treatment she needs.If you have any follow-up questions or concerns, please feel free to reply and I would be more than happy to address them for you. Otherwise, I hope you found this information helpful, and that your girl gets to feeling better soon!